How Do Biocides That Occur in Waste Activated Sludge Affect the Resource Recovery for Short-Chain Fatty Acids Production

Abstract

Anaerobic technology is an efficient and sustainable approach for disposing waste activated sludge (WAS), but the performance is easily affected by environmental conditions. In this study, the potential impacts of chlorhexidine (CHD) and hexadecyltrimethylammonium bromide (HTAB), two highly detected biocides in WAS, on the short-chain fatty acids (SCFAs) generation during anaerobic fermentation were explored. The experimental results indicated that the biocides promoted SCFAs generation unexpectedly, particularly for acetic acid. The accumulation of SCFAs increased from 567.3 mg COD/L in the control to 2144.5 and 3400.0 mg COD/L with low CHD and HTAB exposure (50 mg/L), respectively. However, the enhancing effects were weakened in reactors with high loads of biocides or CHD and HTAB coexistence. Mechanisms exploration revealed that the CHD and HTAB first enhanced the extracellular polymeric substances disruption and then simultaneously accelerated both the hydrolysis and acidification processes while inhibiting the methanogensis. The relative activities of hydrolases, acidogenic enzymes, and bioenergy involved in SCFAs production were significantly enhanced with low biocide dosage. Moreover, the abundances of active microorganisms that participated in the biological hydrolysis and acidification processes were highly enriched in biocide reactors while the acetoclastic methanogens were reduced. This work might be of significance to regulate the WAS fermentation for better resource recovery.

Surfactants Aggravated the Biotoxicity of Fe2O3 Nanoparticles in the Volatile Fatty Acids’ Biosynthesis during Sludge Anaerobic Fermentation

“…WAS fermentation is accomplished and mediated by the metabolic activities of various functional microorganisms. 19 However, the microbial community distribution and metabolic functions in response to the combined effects of such contaminants and their subsequent influences on the VFAs biosynthesis have not been adequately studied. Moreover, the mutual interactions between surfactants and NPs and their contributions to the microbial constitution and metabolic functions shift require further investigation.…”

“…Whether the co-occurrence of NPs and surfactants would affect each fermentation step is still unclear. WAS fermentation is accomplished and mediated by the metabolic activities of various functional microorganisms . However, the microbial community distribution and metabolic functions in response to the combined effects of such contaminants and their subsequent influences on the VFAs biosynthesis have not been adequately studied.…”

“…This study aimed to fill the knowledge gap on the joint effects of surfactants (cetyltrimethylammonium bromide (CTAB) and linear alkyl benzene sulfonates (LAS) based on their category and detection frequency in the environment) , and NPs (Fe 2 O 3 NPs being a model NP due to its frequent detection in WAS) on the WAS fermentation process. The VFA yields’ correlations with the co-occurrence of contaminants, as well as the distinguished impacts on the specific WAS fermentation steps were evaluated.…”

Enhanced biohydrogen generation through calcium peroxide engendered efficient ultrasonic disintegration of waste activated sludge in low temperature environment

“…Contrastingly, the WAS consist of colloidal particles with an enormous amount of organics, and thus, abundant research has been made by utilizing WAS as an efficient substrate for energy generation (Luo et al, 2018;Yuan et al, 2019). The emergent crisis of energy throughout the world leads to the selection of this waste as substrate (Luo et al, 2019;Wei et al, 2017). Anaerobic degradation (AD) is an eco-friendly technology to utilize organic waste for transforming it into energy (Abdelsalam et al, 2017).…”

Performance and Mechanism of Potassium Ferrate(VI) Enhancing Dark Fermentative Hydrogen Accumulation from Waste Activated Sludge

“…Anaerobic fermentation or digestion is currently the conventional method used for WAS treatment, during which sludge reduction, recovery of resources and energy (e.g., organic acids, H 2 , and CH 4 ), and environmental risk relief (e.g., inactivation of pathogenic microbes) can be simultaneously achieved. − However, in view of the protective effect of cell wall/membrane and EPS on sludge cells, organic substances contained in sludge are difficult to release from sludge, causing poor sludge solubilization, which is intensively recognized as the rate-determining step of anaerobic treatment of sludge . Moreover, concentrated toxic and hazardous substances in sludge are difficult to effectively biodegrade during numerous sludge treatments such as anaerobic digestion or fermentation. − For example, Golet et al found that only about 10% of norfloxacin was degraded during sludge anaerobic digestion.…”